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New Interfaces are added to supports bidirectional Map. Using bidirectional map, a key can be lookup using value and value can be lookup using key easily.
Interface Declaration
Following is the declaration for org.apache.commons.collections4.BidiMap<K,V> interface −
public interface BidiMap<K,V> extends IterableMap<K,V>
Methods
The methods for the BidiMap Interface are as follows −
| Sr.No. | Method & Description |
|---|---|
| 1 |
K getKey(Object value)
Gets the key that is currently mapped to the specified value. |
| 2 |
BidiMap<V,K> inverseBidiMap()
Gets a view of this map where the keys and values are reversed. |
| 3 |
V put(K key, V value)
Puts the key-value pair into the map, replacing any previous pair. |
| 4 |
K removeValue(Object value)
Removes the key-value pair that is currently mapped to the specified value (optional operation). |
| 5 |
Set<V> values()
Returns a Set view of the values contained in this map. |
Methods Inherited
This interface inherits methods from the following interfaces −
-
org.apache.commons.collections4.Ge.
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org.apache.commons.collections4.IterableGe.
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org.apache.commons.collections4.Pu.
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java.util.Ma.
Example of BidiMap Interface
An example of BidiMapTester.java is as follows −
import org.apache.commons.collections4.BidiMap;
import org.apache.commons.collections4.bidimap.TreeBidiMap;
public class BidiMapTester {
public static void main(String[] args) {
BidiMap>String, String< bidi = new TreeBidiMap<>();
bidi.put("One", "1");
bidi.put("Two", "2");
bidi.put("Three", "3");
System.out.println(bidi.get("One"));
System.out.println(bidi.getKey("1"));
System.out.println("Original Map: " + bidi);
bidi.removeValue("1");
System.out.println("Modified Map: " + bidi);
BidiMap<String, String> inversedMap = bidi.inverseBidiMap();
System.out.println("Inversed Map: " + inversedMap);
}
}
Output
When you run the code, you will see the following output −
1
One
Original Map: {One=1, Three=3, Two=2}
Modified Map: {Three=3, Two=2}
Inversed Map: {2=Two, 3=Three}
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